1. Technical Field
The present invention relates to a system for decoupling a java virtual machine (JVM) from a browser. Specifically, the invention relates to a system to retain applet security privileges outside of the JVM, thereby allowing internet browser decoupling from the JVM.
2. Description of Related Art
The Internet, also referred to as an “internetwork”, in communications is a set of computer networks, possibly dissimilar, joined together by means of gateways that handle data transfer and the conversion of messages from the sending network to the protocols used by the receiving network (with packets if necessary). When capitalized, the term “Internet” refers to the collection of networks and gateways that use the TCP/IP suite of protocols.
The Internet has become a cultural fixture as a source of both information and entertainment. Many businesses are creating Internet sites as an integral part of their marketing efforts, informing consumers of the products or services offered by the business or providing other information seeking to engender brand loyalty. Many federal, state, and local government agencies are also employing Internet sites for informational purposes, particularly agencies which must interact with virtually all segments of society such as the Internal Revenue Service and secretaries of state. Operating costs may be reduced by providing informational guides and/or searchable databases of public records online.
Currently, the most commonly employed method of transferring data over the Internet is to employ the World Wide Web environment, also called simply “the web”. Other Internet resources exist for transferring information, such as File Transfer Protocol (FTP) and Gopher, but have not achieved the popularity of the web. In the web environment, servers and clients effect data transaction using the Hypertext Transfer Protocol (HTTP), a known protocol for handling the transfer of various data files (e.g., text, still graphic images, audio, motion video, etc.). Information is formatted for presentation to a user by a standard page description language, the Hypertext Markup Language (HTML). In addition to basic presentation formatting, HTML allows developers to specify “links” to other web resources identified by a Uniform Resource Locator (URL). A URL is a special syntax identifier defining a communications path to specific information. Each logical block of information accessible to a client, called a “page” or a “web page”, is identified by a URL. The URL provides a universal, consistent method for finding and accessing this information by the web “browser”. A browser is a program capable of submitting a request for information identified by a URL at the client machine. Retrieval of information on the web is generally accomplished with an HTML-compatible browser.
When a user desires to retrieve a page, a request is submitted to a server connected to a client computer at which the user is located and may be handled by a series of servers to effect retrieval of the requested information. The information is provided to the client formatted according to HTML. Typically, personal computers (PCs) along with work stations are typically used to access the Internet.
Often applications or programs may be sent to a computer from a web server across the Internet. Java applications are becoming increasingly more prevalent as the type of application sent between web servers and client computers. Java applications are common on the Internet and becoming more increasingly common in intranets and in other types of networks used in businesses.
Java is an object oriented programming language and environment focusing on defining data as objects and the methods that may be applied to those objects. Java supports only a single inheritance, meaning that each class can inherit from only one other class at any given time. Java also allows for the creation of totally abstract classes known as interfaces, which allow the defining of methods that may be shared with several classes without regard for how other classes are handling the methods.
The Java virtual machine (JVM) is a virtual computer component that resides only in memory. The JVM allows Java programs to be executed on a different platform as opposed to only the one platform for which the code was compiled. Java programs are compiled for the JVM. In this manner, Java is able to support applications for many types of data processing systems, which may contain a variety of central processing units and operating systems architectures. To enable a Java application to execute on different types of data processing systems, a compiler typically generates an architecture-neutral file format—the compiled code is executable on many processors, given the presence of the Java run-time system. The Java compiler generates bytecode instructions that are non-specific to a particular computer architecture. A bytecode is a machine independent code generated by the Java compiler and executed by a Java interpreter. A Java interpreter is a part in the JVM that alternately decodes and interprets a bytecode or bytecodes. These bytecode instructions are designed to be easy to interpret on any computer and easily translated on the fly into native machine code.
Many currently available web browsers, such as Netscape Communicator, which is available from Netscape Communications Corporation, incorporate fixed, embedded JVMs in which the browsers pass fixed options to the JVM. Presently, however, JVMs updates are provided more often than web browser updates. Such a situation prevents users from taking advantage of improved versions of JVMs until the web browser is updated. Therefore, it would be advantageous to have an improved method and apparatus for providing users an ability to use more recent versions of JVMs without having to wait for an updated version of the web browser. Specifically, a fixed JVM within the browser limits the flexibility of developers and users of Java applets within the browser. “Applets” are mini applications that typically run inside a Java-enabled browser.
Netscape implements a proprietary Java security scheme within their browser (and JVM). Applets can request, and subsequently be granted certain privileges, such as being able to read or write to the local hard drive. These privileges, when granted, are stored in the JVM's call stack frame which corresponds to the method which has been granted access. These privileges remain in effect until the method (function) which requested it goes out of scope. In other words, when the function is popped from the call stack. These privileges are also removed when a user explicitly reverts the privilege.
The implementation of storing privileges on the JVM's stack frame requires JVM modifications for its implementation, since the stack frame data structure is internal to the JVM. This implementation prevents the usage of a de-integrated JVM. Netscape has also changed many system Java classes to explicitly code enable Privilege/revert Privilege calls. By doing so, a copy of a Java source file for a given level of Java is modified with these calls to enable or revert privileges. This locks the browser into a particular level of Java source.
Therefore, a need exists for a method of decoupling the JVM from the browser. Once decoupled, a more up-to-date version of the JVM can be utilized. However, applet security privileges must be retained outside of the JVM by such a system.